Interactions with an interface, such as human touch interaction with an image projected or otherwise displayed on a surface, can be detected by many means. Such previous methods of detecting interactions included digital cameras (e.g., charge-coupled device (CCD) cameras or CMOS cameras) that continuously capture images of a scene and continuously process the scene to determine the occurrence and location of an interaction with the interface. These solutions, however, require the use of one or more extra cameras and associated optics to monitor the scene, which can be an expensive addition and can be difficult to incorporate into a small form factor as may be needed for implementation in portable electronic devices such as mobile communication devices. Further, these solutions require a large amount of processing power to process the images of a scene and consume additional power to operate the camera and to process the data. Further still, camera-based solutions perform poorly under harsh ambient light conditions.
Other methods involve lasers or other distance measurement equipment to constantly measure distances of objects within the measurement field to determine if an interaction occurs. However, these solutions also require the extra components needed to effectuate the distance measurements, which can be costly, power hungry, and too large for use with smaller portable devices. Still other solutions use ultrasound technology or electro-magnetic sensing. However, these solutions do not provide accurate readings as to the location of an interaction.
Given the proliferation of mobile and wireless devices, a solution that provides accurate interaction detection while minimizing processing power, power consumption, and physical form factor is desirable.